When an opening in tissue is created either through an intentional incision or an accidental wound or laceration, biological healing of the opening commences through the proximity of the opposed living tissue surfaces. If the opening is very large or if its location subjects the wound to continual movement, a physician will seek to forcibly hold the sides of the opening in close proximity so as to promote the healing process.
In the case of skin tissue, for example, healing occurs best when the opposing dermal layers of the skin tissue are held in proximity with each other. Human skin tissue is comprised of three distinct layers of tissue. The epidermal layer, also known as the epidermis, is the outermost layer and includes non-living tissue cells. The dermal layer, or dermis, is the middle layer directly below the epidermal layer and comprises the living tissue of the skin that is the strongest of the three layers. The subcutaneous, or hypodermis layer is the bottom layer of skin tissue and includes less connective tissue making this the weakest layer of skin tissue.
The most prevalent method for forcibly closing a tissue opening is through the use of a suture or “stitches.” As early as the second century, the Greeks were using sutures to physically close skin openings. In its simplest form, a suture is simply a length of material that is attached to a tissue-piercing device, such as a needle, and looped through the opposing sides of an opening. The suture is then pulled tight and the loop closes causing the opposing sides of the tissue to come into close physical proximity. The suture loop is held tight by the tying of a knot or some other locking mechanism. The first sutures were made of animal gut. Eventually other natural suture materials including leather, horsehair, flax, cotton and silk came into use.
As the sciences of medical and materials technology have advanced over the course of the past century, new bioabsorbable materials have been developed to further improve upon the basic suturing concept. Examples of modem improvements to the suturing process include enhancements to the suturing apparatus as shown, for example, in U.S. Pat. Nos. 755,921, 2,439,383, 2,959,172, 3,344,790 and 3,633,582, as well as advances in sutures and suture materials as shown, for example, in U.S. Pat. Nos. 3,123,077, 3,297,033, 3,636,956, 3,792,010 4,027,676 and 4,047,533. More recently, the suturing apparatus has been improved in the way of developing surgical “sewing machines” as shown, for example, in U.S. Pat. Nos. 5,496,334, 5,728,112, 5,735,862, 5,876,412, and 6,332,889, as well as in U.S. Publication Ser. Nos. 20030171761A1 and 20030216755A1. In addition, the suturing apparatus has been improved and tailored for specialty applications, for example endoscopic applications as shown, for example, in U.S. Pat. Nos. 5,080,663, 5,389,103, 5,522,820, 5,578,044, 5,674,230, 5,797,927, 5,817,110, 5,871,488, 5,938,668, 5,976,161, and 6,641,592, as well as in U.S. Publication Ser. Nos. 20020049453A1, 20020065526A1, 0020128666A1, 20030105475A1, 20030105476A1, and 20030114863A1. Finally, suturing applications have been developed in which a secondary tissue fixation method is used in conjunction with a suture as shown, for example, in U.S. Pat. Nos. 6,264,675 and 6,478,809.
While suturing remains a popular method of effectuating closure of skin openings, the use of staples and staplers as a skin closure technique has become increasingly popular, especially in surgical settings where the opening is created through a purposeful incision. In these settings, the incision tends to make a clean, straight cut with the opposing sides of the incision having consistent and non-jagged surfaces. Typically, stapling of a skin opening, for example, is accomplished by manually approximating the opposing sides of the skin opening and then positioning the stapler so that a staple will span the opening. The stapler is then manipulated such that the staple is driven into the skin with one leg being driven into each side of the skin and the cross-member of the staple extending across the opening external to the skin surface. Generally, the legs of the staple are driven into an anvil causing the staple to deform so as to retain the skin tissue in a compressed manner within the staple. This process can be repeated along the length of the opening such that the entire incision is held closed during the healing process.
Much work has been devoted to improving upon the basic stapling process. Developments have gone in a variety of directions and include work devoted to the stapling apparatus as shown, for example, in U.S. Pat. Nos. 3,082,426, 3,643,851, 4,410,125, 4,493,322, 4,592,498, 4,618,086, 4,776,506, 4,915,100, 5,044,540, 5,129,570, 5,285,944, 5,392,979, 5,489,058, 5,551,622, 5,662,258, 5,794,834, 5,816,471, 5,893,855, 6,131,789, 6,250,532 and 6,283,984. In addition to the stapling apparatus, developments have also been made in the staple design as shown, for example, in U.S. Pat. Nos. 2,351,608, 2,526,902, 2,881,762, 3,757,629, 4,014,492, 4,261,244, 4,317,451, 4,407,286, 4,428,376, 4,485,816, 4,505,273, 4,526,174, 4,570,623, 4,719,917, 4,741,337, 5,007,921, 5,158,567, 5,258,009, 5,297,714, 5,324,307, 5,413,584, 5,505,363 and 5,571,285.
In some instances, work has been devoted to combining the advantages of sutures and staples into a single medical fastener for purposes of wound closure. Various different styles and techniques of combining sutures and staples have evolved as shown, for example, in U.S. Pat. Nos. 5,342,376, 5,425,747, 5,584,859, 5,931,855, 6,106,544, 6,270,517, and 6,599,310.
While modern suturing and stapling techniques continue to provide an effective manner of effectuating skin closure, there remains a series of inherent disadvantages in using either of these techniques. The standard technique for both suturing and stapling includes puncturing both the epidermis and dermis. This can result in a wound closure having an unaesthetically pleasing appearance on the surface of the skin. The presence of the fastener exposed through the skin surface provides an opportunity for infection and for accidentally catching the fastener and tearing the wound open. In the case of non-absorbable fasteners, further action by a medical professional is necessary in order to remove the fastener once biological healing is complete.
In order to overcome these limitations, practitioners have developed a number of specialized suturing techniques where the suture is passed only through the dermis effectively positioning the suture below the skin surface, or in a subcuticular fashion. A surgeon has the choice of placing individual or interrupted sutures along the length of an opening. Another suturing option is for the surgeon to use a single strand of suture material to place a plurality of continuing suture loops or running sutures along the length of an opening. While the presence of the suture below the surface can improve the aesthetic nature of the closure, it requires greater skill and technique to accomplish effectively and takes longer than conventional external suturing.
While there has been active development of dermal layer suturing techniques, little has been done in the area of staples and staplers for use in connection with the dermal layer. In a series of patents issued to Green et al., including U.S. Pat. Nos. 5,292,326, 5,389,102, 5,489,287 and 5,573,541, a subcuticular stapling method and apparatus are disclosed that were ultimately commercialized as the U.S. Surgical SQS Subcuticular Stapling Apparatus. The Green et al. patents describe a stapling technique employing a handheld apparatus with jaws to proximate, interdigitate and overlap opposing sides of dermal layer tissue along the length of a skin opening. The apparatus then drives a single spike through the interdigitated and overlapped dermal layers of the opposing skin surfaces in order to secure both sides of the dermal tissue on the single spike. Although this technique reduced the time required to effectuate a subcuticular skin closure, the SQS device was not commercially successful in part because the resulting closure produced an undesirable wave-like scar that sometimes did not heal effectively.
Another alternative bioabsorbable approach is disclosed and described in a series of patents issued to Brotz, including U.S. Pat. Nos. 5,425,747, 5,584,859, 6,270,517 and 6,478,809. The Brotz patents describe a suturing technique using a bioabsorbable suture structure having a plurality of lateral members extending perpendicularly from a central body member. Lateral members on opposed sides of the central body extend into tissue on opposing sides of an incision whereby the lateral members hold the incision closed.
Another bioabsorbable approach for wound closure is disclosed and described in U.S. Pat. No. 6,645,226 that comprises a series of attachment points projecting from a common supportive backing. The backing is then placed below the wound, generally in the sub-dermal layer, such that the backing extends across the wound. Next, the tissue is pressed over the attachment points such that the wound stress is distributed by the backing.
In yet another bioabsorbable approach for wound closure, U.S. Pat. No. 6,599,310 to Leung et al., describes a barbed suture that can be used for approximating and retaining subcuticlar tissue during the healing process. The barbed suture can be looped by a surgeon through opposing sides of a tissue wound, along the length of the wound, whereby the suture is pulled tight and the wound is held closed.
Unfortunately, none of these bioabsorbable fasteners designed for use in the dermal layer have achieved significant commercial or medical success.
A novel bilateral approach to fastening dermal tissue using bioabsorbable fasteners is disclosed and described in U.S. Pat. No. 6,726,705, as well as in U.S. patent application Ser. Nos. 10/448,838, 10/607,497 and 10/603,397, to Peterson et al, all of which are commonly assigned to the assignee of the present application and all of which are incorporated by reference in their entirety. This bilateral approach to tissue fastening first manipulates opposed sides of tissue to form target tissue zones followed by a bilateral insertion of a tissue fastener to retain opposed dermal layers across an incision or wound in close approximation to facilitate healing. By maintaining contact of the dermal layers through the healing process, the healing process is enhanced which results in less chance of infection, faster recovery and improved aesthetic appearance. In addition, no subsequent medical follow-up is necessary to remove fasteners as is typically necessary with nonabsorbable fasteners.
While the bilateral tissue fastening methods and apparatus taught by Peterson et al. provide many advantages, it would be advantageous to extend the principles taught by Peterson et al. to other suitable tissue fastening applications.